The Zipper is one of Waluigi's three Karts in Mario Kart DS. The other two are the Standard WL and Gold Mantis. It has average stats, all of which except for weight and items are slightly lower than his other karts.
The Zipper has two black back tires and one in the front, each with yellow rims. Two white bumpers, similar to the ones on the Standard Karts on Mario Kart DS, are on either side of the vehicle. The metallic body is mainly gray, and the engine can be seen in the lower front part of the frame. The steering wheel and seat are brown, and the chair is reclined back (that looks really comfy...). The hood of the motorcycle displays Waluigi's logo, an upside down "L". Two clasps hold to metal bars in place, which slant down to hold the front tire in the axel.
This happens to be the first Bike in the Mario Kart series. Even though it cannot do Wheelies like Bikes can do in Mario Kart Wii, it still retains the appearance of a Bike. However, it is called a Kart in Mario Kart DS. But no matter what the game developers say it is, just remember... it is a Bike.